History Main / ItOnlyWorksOnce

* ''Franchise/SpiderMan'':
** This ended up happening by the eighth or so issue of ''The Amazing Spider-Man''. In the Vulture's first appearance, Spider-Man took him down by simply clipping his wings with a device designed to cancel out the magnetic harness that allowed him to fly. Not so in their second encounter, where the Vulture puts in a fail-safe to get around this, and sucker-punches Spidey the minute he isn't looking.

** In an old ''Marvel Team-Up'' issue, ComicBook/BlackPanther concocted a super strong web fluid to hold Stegron, a villain that had previously broken out of Spider-Man's webs. It was stated that the new serum was very unstable, and Black Panther himself warned Spider-Man that it could only be used on this one occasion.

* ''Franchise/{{Superman}}'':

* Tony's badass [[spoiler:wrist-lasers]] in ''Film/IronMan2''. {{Justified|Trope}} when we see [[spoiler: Tony eject a pair of smoking doohickies from his gauntlets after firing the lasers. The single shot clearly burns the doohickies out, leaving him physically unable to use the weapon again at the time. Since he doesn't grab a new pair of doohickies out of a storage compartment, we can assume that re-readying the lasers requires more than a simple doohicky swap.[[InherentlyFunnyWords Doohicky]]]]. Lampshaded by Tony himself when [[Characters/IronManHeroes Rhodey]] says he should have led with that: "It's a one-off."
** And then averted in [[Film/MarvelsTheAvengers the next movie]], when Tony uses the Mark VII suit in the climax: not only does his wrist-mounted lasers now have three beams, but after he uses them, they retract into his gauntlet, presumably to be used again later.

* In the ''[[Series/Merlin2008 Merlin]]'' fic "[[https://www.fanfiction.net/s/11802781/30/Shades-of-Destiny Shades of Destiny]]", Merlin [[spoiler:is able to bring Arthur back to life after the Battle of Camlann by pleading with the Goddess that he and Arthur need to form Albion and there has been enough death to justify restoring this one life, but Merlin senses a warning from the Goddess even as Arthur is restored that he'll only be able to get away with such a resurrection this once]].

* Tony's badass [[spoiler:wrist-lasers]] in ''Film/IronMan2''. {{Justified|Trope}} when we see [[spoiler: Tony eject a pair of smoking doohickies from his gauntlets after firing the lasers. The single shot clearly burns the doohickies out, leaving him physically unable to use the weapon again at the time. Since he doesn't grab a new pair of doohickies out of a storage compartment, we can assume that re-readying the lasers requires more than a simple doohicky swap. [[InherentlyFunnyWords Doohicky]]]]. Lampshaded by Tony himself when [[Characters/IronManHeroes Rhodey]] says he should have led with that: "It's a one-off."

* In ''Film/BackToTheFuturePartII'', to prevent Jennifer from asking too many questions about her future, Doc [[InstantSedation uses a sleep-inducing device to tranquilize her]]. Unfortunately, this causes a minor crimp in his plan to have Marty take his son's place at a meeting with Griff as the inducer didn't have enough power left to knock Marty Jr. out for a full hour, resulting in him showing up.

* This is a matter of some contention among ''Literature/TheLordOfTheRings'' fandom, among whom there is a vocal minority that considers Aragorn's use of a seemingly invincible undead army in only one battle (rather than throughout the war) to be a Headscratcher verging on a Wall Banger. Debates about whether the ExactWords of their oath would have allowed him to demand longer service from them can go (and have gone) on for dozens of pages in various internet fora. The popular consensus is that the undead army was not magically compelled to obey Aragorn, but did so voluntarily as he was the only one who could release them to pass on to a more standard afterlife. If they'd gotten it into their heads that he did not intend to release them, they could very well have gone over to the other side, so he decided that it was better to be safe than sorry. YMMV on whether this explanation makes this a legit example or is merely a convenient bit of FanWank. It should also be noted that it is never made clear (in the books at least) if the army of the dead can ''physically'' hurt people, as the only army they deal with they simply terrify into fleeing. If they could not actually attack people, once the psychological impact of them wore off, their usefulness would be greatly reduced. Regardless, they demanded to be released after a single battle, and he complied.

* In an issue of ''ComicBook/UncannyXMen'' [[Characters/MarvelComicsRogue Rogue]] absorbed [[Characters/MarvelComicsNightcrawler Nightcrawler]]'s powers and defeated Nimrod, the mutant killing robot from the future, by teleporting a chunk of his body away. The next time the X-Men fought Nimrod, Nightcrawler simply tried the same trick again, only to discover that Nimrod had adapted himself so that not only did it not work but the attempt messed Nightcrawler up quite badly.

* ''Fanfic/ThisBites'': Franky runs into this problem when trying to push Monster Point Chopper into the sea thanks to Chopper's enchanced intelligence [[AdaptationalIntellignece making his normally animalistic form far more adaptable than canon]]. Any attacks that Franky uses will only work the first time, as Monster Point Chopper will then come up with a strategy to counter it (such as dodging the cyborg's Weapon Left or blocking Fresh Fire with his hooves).

[[folder:Film - Animated]]

[[folder:Film - Live Action]]

-->-- ''WesternAnimation/JusticeLeague''

* The [[ExactlyWhatItSaysOnTheTin aptly-named]] "Henshin One-Shot" from the NonSerialMovie of ''Series/KamenRiderFaiz'' lets a normal human {{henshin|Hero}} into [[TheLancer Kamen Rider Kaixa]] exactly once. And that is because [[spoiler: instead of [[InvertedTrope the user suffering the after-effects]], it dissolves the [[TransformationTrinket Kaixa Gear]] by overclocking.]]

* ''[[WesternAnimation/JusticeLeague Justice League Unlimited]]'':
** After The Flash defeated Brainthor by tapping into the Speed Force, he said he didn't think he'd come back if he went that fast again. Notably, when another version of the Flash in the comics did something similar, he ''didn't'' come back.
** Amazo was able to adapt so that kryptonite didn't work on him.
** Shadow Thief was weak against bright lights in his first appearance. In his second appearance, he comments light hasn't worked on him in months.
** This was actually used in the pilot, when Flash asks Martian Manhunter [[StatingTheSimpleSolution why he doesn't use the nerve gas he used to defeat the Imperium before]]. Manhunter explains [[SimpleSolutionWontWork it can only be made from a rare Martian plant]], and [[TaughtByExperience the only sample of it he had was destroyed when he got captured]].
* In ''WesternAnimation/KimPossible'' episode "Queen Bebe", Kim encounters the Bebe robots she had faced in "Attack of the Killer Bebes", which she managed to defeat by disabling them with a high-pitched frequency. Unfortunately, when she tries to use it again, she found it had no affect.

** In ''ComicBook/TheLastDaysOfSuperman'', Supergirl uses a piece of Red Kryptonite, which restores a Kryptonian's powers on planets with a red sun (found by Superboy in ''ComicBook/Superboy1949'' #81), to keep her powers when she time-travels to pre-destruction Krypton. As all fragments of Red Kryptonite, though, it only has effect on each Kryptonian once; so neither Kara nor Kal were able to use it again.

*** TMs are back to being single-use in Generation IX, though players are now able to create more whenever they want as long as they have the materials for it.

** Burn Up requires the user to be a Fire-type to use, and causes them to stop being Fire-type when used.

* ''Fanfic/HarryPotterAndTheNatural20'': Milo is a D&D-style wizard and a massive munchkin, so he loves coming up with inventive ways to accomplish things using methods that should not, really, work like that. [[note]]A prime example is his party sneaking into a castle by hiding behind tower shields, since having full cover makes you untargetable and not in line-of-sight, which amounts to being invisible, and extends to all your equipment ''including said tower sheild''.[[/note]] He's fully aware, however, that reality itself will quickly thereafter come up with a rule change that makes the trick unworkable, so he only gets a single shot.

* ''Fanfic/HarryPotterAndTheNatural20'': Milo is a D&D-style wizard and a massive munchkin, so he loves coming up with inventive ways to accomplish things using methods that should not, really, work like that. [[Note]]A prime example is his party sneaking into a castle by hiding behind tower shields, since having full cover makes you untargetable and not in line-of-sight, which amounts to being invisible, and extends to all your equipment ''including said tower sheild''.[[/note]] He's fully aware, however, that reality itself will quickly thereafter come up with a rule change that makes the trick unworkable, so he only gets a single shot.

* In the ''Overwatch'' League 2018, Los Angeles Gladiators pull off the [[https://youtu.be/BjCUTAg2eUQ "Great Bamboozle"]] stradegy by pretend to be a GOATS comp to trick the London Spitfire to engage while their defense wide open for Gladiator's sniper to pick off crucial DPS and support wins the first game. 9 hours later in Overwatch Contender, GC Busan Wave tries to replicate the Gladiator's stradegy, but their enemy team Seven immedetly predit this and counter accordingly. Even the [[https://youtu.be/2vULJrUez6o?t=991 commentators]] sums up this plan only works once.

* In ''Film/BackToTheFuturePartII'', to prevent Jennifer from asking too many questions about her future, Doc uses a sleep-inducing device to tranquilize her. Unfortunately, this causes a minor crimp in his plan to have Marty take his son's place at a meeting with Griff as the inducer didn't have enough power left to knock Marty Jr. out for a full hour, resulting in him showing up.

* Much like the RealLife example below, ''LightNovel/TheFamiliarOfZero'' pulls this with the Wand of Destruction. Only Saito can use it, and it only works once. It's really an M72 LAW rocket launcher and it has one shot, so when [[spoiler:Longueville]] aka Fouquet tries to use it on Saito, it doesn't work.

* In ''WesternAnimation/TheIncredibles'', The Omnidroid is a learning robot, and combined with Syndrome's constant upgrades, it's able to defeat superhero after superhero, with anyone who defeats it getting killed by the next model. We even see Mr. Incredible attempting a "jump over the robot" avoidance maneuver twice and being completely thwarted on the second attempt. His ImprovisedWeapon of the Omnidroid's own detached claw only gives him one chance to take it out.

* ''Film/{{Deadpool 2}}'': Deadpool asks Cable why he can't use his time travel device to just keep bouncing around time until he gets everything right. Cable says his device only has enough charge left for one more jump, which he needs to get back home.

* Leet, a GadgeteerGenius in ''Literature/{{Worm}}'', has this as an explicit part of his superpower. He can invent a machine to fulfill any function... once. The second time it just explodes.

** In one of his ''Pyramid'' editiorials, Steven Marsh said that he'd tried giving his players awesome abilities that could only ever be used once, and they never got used at all. Partly because players were always thinking that if they used it now, they might need it later, until not using it became a habit, and partly because it's just so much cooler to be the guy who could ''at any moment'' unleash their Ultimate Power than it is to be the guy who did that three adventures ago.

* ''Fanfic/RosarioVampireBrightestDarkness Act III'': While the group is fighting Kuyou in chapter 41, Mizore and Kurumu manage to land a blow on him with their [[CombinationAttack duet]]. In chapter 42, when they try the attack again, Kuyou isn't about to let it happen twice and disrupts the attack by [[LauncherMove throwing Moka at them]].

* ''Fanfic/{{Marionettes}}'': The first time Trixie faces Gear Shift and Cover Story, she covers the floor with ice to make them slip. In their second encounter, when she tries it again, they're wearing winter horseshoes that allow them to walk on ice.
* In an [=AU=] retelling of the ending of ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' episode "[[Recap/MyLittlePonyFriendshipIsMagicS4E7Bats Bats!]]" entitled "[[http://www.fimfiction.net/story/347603/you-look-so-sexy-this-way You Look So Sexy This Way]]", it's revealed that the spell Twilight used on the vampire fruit bats can only affect a subject once. However, the attempt to return Flutterbat to normal only restored Fluttershy's senses, with her body still being that of a batpony, and because Fluttershy receiving the rebound from the bats counted as being cast, the spell would no longer work on her, leaving her a batpony permanently.

* Downplayed in ''Fanfic/AmazingFantasy''. Izuku can only use his Venom Strike once a day, limiting him to one usage of it in any given fight, but he'll be able to use it again after a full night's rest.
* ''Fanfic/FalloutEquestria'': Alicorns have a whole suite of powerful magical abilities, plus a HiveMind. Therefore, any time Littlepip finds a way to trick around their [[ImmuneToBullets impregnable shields]], next time they're ready for it. Stealth is the preferred method of dealing with them, but it's not always an option since they're often the ones ambushing her.
* In the ''[[Series/Merlin2008 Merlin]]'' fic "[[https://www.fanfiction.net/s/11802781/30/Shades-of-Destiny Shades of Destiny]]", Merlin [[spoiler:is able to bring Arthur back to life after the Battle of Camlann by pleading with the Goddess that he and Arthur need to form Albion and there has been enough death to justify restoring this one life, but Merlin senses a warning from the Goddess even as Arthur is restored that he'll only be able to get away with such a resurrection this once]].

* Discussed in "[[https://archiveofourown.org/works/25601596/ Honey and Magic]]", when [[Literature/{{Matilda}} Matilda Honey]] talks with [[Franchise/HarryPotter Fred and George Weasley]] about possible methods of getting rid of Umbridge by discussing Matilda's own experiences with Miss Trunchbull. While the twins admire her tale of how she drove Trunchbull out after hearing about the headmistress's cruelty, they note that Umbridge's political connections at the Ministry basically give her more power than Trunchbull, as Umbridge can rely on support from Fudge whereas Trunchbull would have faced serious trouble if she was ever subject to an official investigation by impartial outsiders to the school.
* The idea of this is essentially analysed in "[[https://www.fanfiction.net/s/10987368/1/Always-a-Ranger Always a Ranger]]", an AU of [[Recap/PowerRangersOperationOverdriveS1E20OnceARangerPart1 the confrontation with Thrax]] where he attacked [[Series/PowerRangersSPD the SPD B-Squad]] rather than the Operation Overdrive team. After Thrax depowers the current SPD Rangers (minus the Omega Ranger, who was dealing with another situation at the time), the Sentinel Knight cannot repair the Morphing Grid to restore SPD's powers, but he is able to reach back through time and draw five past Rangers into the present while restoring their abilities as a substitute team. When Thrax is asked why he can't just depower these Rangers as well, Thrax acknowledges that he ''could'' do that, but since the Sentinel Knight would just repeat what he's just done and draw a new team of past Rangers in as a substitute group, there wouldn't be any point to that approach, so it's best that they focus on finding a way to stop the Sentinel Knight before worrying about depowering the Rangers again.
* Basically applies in ''Fanfic/TheCorruptedInnocent'' when Bela learns that her status as an unbroken Seal means that she is essential "immune" to Lucifer's powers; just as he couldn't break the Seals himself, Bela is basically immune to direct assault from Lucifer's powers (he can throw things ''at'' her but he can't attack her directly), and he's also unable to read her mind or sense her presence with anything but his human senses. However, Castiel warns Bela that Lucifer will be on his guard once he ''knows'' about her immunity, so Bela decides to take care when confronting Lucifer, waiting for the right moment when being able to take action against Lucifer and catch him by surprise will be genuinely useful, as opposed to just buying them the advantage for that moment and never again.
* In the Franchise/MarvelCinematicUniverse/''Franchise/HarryPotter'' crossover "[[https://archiveofourown.org/works/26698570/ Strange Potter]]", when Doctor Strange purges the horcrux from the infant Harry Potter, he soon realises that his actions have granted Harry the ability to wield chaos magic similar to the Scarlet Witch. Wong observes that such a feat should be impossible as nobody can wield all those magics at once without exploding, but Strange speculates that it was due to a combination of factors such as Lily's protection still being fresh, Harry's natural magic, the dark energy of the horcrux, Strange's own powers, and the natural significance of Halloween to their culture. Strange also explicitly notes that he doubts he could do such a thing again without it being fatal to the subject, as all those events coming together so perfectly was essentially a fluke.
** On a smaller scale, after Natasha Romanoff marries Sirius Black, an extensive treatment of potions and spells allows her to give birth to a son, Regulus, but the healers all state that it's unlikely she'll be able to have another child as healing organ damage like that is very difficult.
* In ''Fanfic/TheWeaverOption'' Taylor's forces are able to successfully kill [[spoiler:Slaanesh]] during the razing of [[spoiler:Commorragh]]. Afterwards Taylor is warned that they only succeeded due to the very unique relationship between [[spoiler:Slaanesh and Commorragh]]. The other [[spoiler:Chaos Gods]] are both better protected and now on-guard against similar strategies.

* In ''{{Fanfic/Luminosity}}'', Elspeth's ExpositionBeam power can be weaponized by sending [[MySkullRunnethOver a massive amount of memories]] to someone at once (specifically, [[spoiler:all the memories Aro has ever read]]), but this can only be used on any given target once. Future attempts do essentially nothing, because the person receiving the memories would have already received them.

* In ''Literature/RomanceOfTheThreeKingdoms'' Zhuge Liang use of the "Empty Fort Strategy". Specifically, he orders his few hundred soldiers to dress as civilians and all the city gates to be thrown open. Sima Yi is wary of Zhuge Liang's strategic brilliance and assumes it to be a triple bluff as Zhuge Liang's plans never leave his army open to this kind of risk. Afterward, Zhuge Liang remarks that the only reason the trick worked is that Sima Yi never imagined that he would try a bluff like that, and now that he has, Sima Yi's too smart to fall for it ever again.